Heretofore, vehicles have been provided with various loads for different uses, such as light sources used as vehicle-mounted exterior lamps including headlights, taillights, and the like.
For example, in a vehicle 100 shown in FIG. 1, a front lamp unit 120 is provided on each of the left and right sides of the front face of a vehicle body 110. The front lamp unit 120 includes, as loads, a headlight, a light source L (hereinafter denoted by sign L3 as needed) which is used as a width indicator, and a light source L (hereinafter denoted by sign L4 as needed) which is used as a blinker (winker). The headlight includes a light source L (hereinafter denoted by sign L1 as needed) for emitting a passing beam (also called a low beam), and a light source L (hereinafter denoted by sign L2 as needed) for emitting a driving beam (also called a high beam). As the light source L1, a high-intensity discharge lamp (HID lamp) or the like is used. As the light sources L2 to L4, halogen lamps or the like are used.
These light sources L1 and L2 are lit or extinguished in accordance with an operation by a user (mainly, driver). Electric power needed for the operation thereof is supplied from a battery (generally 12V) which is an unillustrated vehicle-mounted DC power supply. It should be noted that since the vehicle 100 shown in FIG. 1 includes as the light source L1 a high-intensity discharge lamp as described above, the vehicle 100 includes a lighting device 130 to generate power (AC power) for lighting the light source L1 from the electric power obtained from the battery.
Further, in the vehicle 100 shown in FIG. 1, the light sources L are lit or extinguished by the relay/fuse box 200 which distributes electric power from the vehicle-mounted battery to the loads. The vehicle-mounted battery is provided with multiple power lines S1 to S3. These power lines S1 to S3 are supplied with power under different conditions. For example, the power line S1 is a power line which is connected directly to a higher-potential terminal (positive terminal) of the battery and is always supplied with power. On the other hand, the power line S2 is connected to the battery through a switch or the like which is on when an ignition is on. The supply of power to the power line S2 is started when a user performs an operation for turning on the ignition, and is stopped when a user performs an operation for turning off the ignition. In other words, the power line S2 is a power line being activated in conjunction with the switch for the ignition. Moreover, the power line S3 is connected to the battery through a switch or the like which is turned on or off in accordance with the on/off of an engine. The supply of power to the power line S3 is started when a user performs an operation for turning on the engine, and is stopped when a user performs an operation for turning off the engine. In other words, the power line S3 is a power line being activated in conjunction with the switch for the engine.
As shown in FIG. 1, the relay/fuse box 200 includes a relay RY1 interposed between the lighting device 130 for lighting the light source L1 and the power line S1. When the relay RY1 is on, power is supplied from the power line S1 to the lighting device 130. Thus, the lighting device 130 generates AC power for lighting the light source L1, and supplies the AC power to the light source L1. As a result, the light source L1 is lit. On the other hand, when the relay RY1 is off, power is not supplied from the power line S1 to the lighting device 130. Accordingly, the lighting device 130 cannot generate AC power for lighting the light source L1, and the light source L1 is extinguished.
The relay/fuse box 200 further includes a relay RY2 interposed between the power line S1 and the light source L2, a relay RY3 interposed between the power line S1 and the light source L3, and a relay RY4 interposed between the power line S1 and the light source L4. In accordance with the on/off of each of these relays RY2 to RY4, the corresponding one of the light sources L2 to L4 is lit or extinguished.
These relays RY1 to R4 are turned on and off by a relay control unit (not shown) which is provided in the relay/fuse box 200 and which includes a microcomputer or the like. This relay control unit is connected to transmission lines N of an in-vehicle network such as a CAN (Controller Area Network). The relay control unit performs switching control (on-off control) on the relays RY1 to RY4 on the basis of vehicle information received through these transmission lines N. For example, the relay control unit turns on the relay RY1 when a user performs an operation for turning on the passing beam (turning on the light source L1), and turns off the relay RY1 when a user performs an operation for turning off the passing beam. Moreover, the relay control unit turns on/off the relay RY2 when a user performs an operation for turning on/off the driving beam (turning on/off the light source L2), turns on/off the relay RY3 when a user performs an operation for turning on/off the width indicator, and turns on/off the relay RY4 when a user performs an operation for turning on/off the blinker.
The relay/fuse box 200 further includes a fuse H1 interposed between the power line S1 and the relay RY1, a fuse H2 interposed between the power line S1 and the relay RY2, a fuse H3 interposed between the power line S1 and the relay RY3, and a fuse H4 interposed between the power line S1 and the relay RY4. These fuses H1 to H4 are provided to prevent a short-circuit or the like from causing the followings: a decrease in the voltage of the battery leads to such a shortage of battery voltage that the vehicle 100 will be rendered inoperative; and a large current flow results in smoking or firing or brakes a light source L.
In the vehicle 100, as shown in FIG. 2, rear lamp units 140 are provided as well as the front lamp units 120. The rear lamp units 140 are provided respectively on the left and right sides of the rear face of the vehicle body 110 of the vehicle 100. The rear lamp units 140 each include a light source L (hereinafter denoted by sign L5 as needed) for a backup light (reversing light), a light source L (hereinafter denoted by sign L6 as needed) which is used as a taillight (tail lamp) or a stop light (also called a brake light or a brake lamp) by changing the intensity, a light source L3 which is used as a width indicator, and a light source L4 which is used as a blinker. As the light sources L5 and L6, for example, incandescent lamps (incandescent bulbs) such as halogen lamps are used. Further, the above-described light sources L3 to L6 of the rear lamp unit 140 are also lit and extinguished by the relay/fuse box 200.
In recent years, there has been widespread introduction of electronics into vehicles. Vehicles are equipped with various control systems for improving driving safety. For example, vehicles are equipped with control systems for implementing systems such as ARS (Advanced Rearlighting System) with which an emergency braking in an emergency causes brake lamps to flash to inform a following vehicle of the status of a vehicle in more detail, and AFS (Adaptive Frontlighting System) which greatly improves visibility for a driver during night driving by emitting light in the direction of gaze or the turn direction of a vehicle at the time of cornering (e.g., see Patent Documents 1 and 2).
The implementation of AFS requires loads for changing the orientation and the like of light sources in accordance with the environment of the vehicle. For example, in the vehicle 100 shown in FIG. 1, a swivel motor M1 for turning the optical axis of the light source L1 to the right and left, and a leveling motor M2 for adjusting the vertical position of the optical axis of the light source L1 are provided as loads for changing the orientation and the like of light sources in accordance with the environment of the vehicle. Moreover, in the vehicle 100, a motor controller 150 is provided for use in the control of operation of the swivel motor M1 and the leveling motor M2.
The motor controller 150 is connected to the transmission lines N of the in-vehicle network as is similar to the relay control unit. Based on vehicle information and the like received through these transmission lines N, the motor controller 150 controls the swivel motor M1 and the leveling motor M2. For example, when the vehicle 100 passes through a curve, the motor controller 150 controls the swivel motor M1 to turn the optical axis of the light source L1 so that the light source L1 may emit light in the travelling direction of the vehicle 100. Moreover, the motor controller 150 also controls the leveling motor M2 so that the position of the light source L1 may be kept constant with respect to the road surface even when there is a change in road surface conditions or the number of passengers.
Since operating power for the above-described motor controller 150 is also supplied from the vehicle-mounted battery, the supply of power from the battery to the motor controller 150 are started and stopped by the relay/fuse box 200. For these functions, the relay/fuse box 200 is further provided with relays RY5 and RY6 individually interposed between the motor controller 150 and the power line S2, and a relay RY7 interposed between the motor controller 150 and the power line S3, in addition to the above-described relays RY1 to RY4 and fuses H1 to H4. The relay/fuse box 200 further includes a fuse H5 interposed between the relay RY5 and the power line S2, a fuse H6 interposed between the relay RY6 and the power line S2, a fuse H7 interposed between the relay RY7 and the power line S3, and a fuse H8 interposed between the motor controller 140 and the power line S1. Moreover, the above-described relay control unit also has the function of performing switching control on the relays RY5 to RY7 on the basis of vehicle information and the like received through the transmission lines N of the in-vehicle network.
Patent Document 1: JP-A 2006-7987
Patent Document 2: JP-A 2006-7988
As described above, in recent years, vehicles have been increasingly provided with loads (e.g., a swivel motor, a leveling motor, an acceleration sensor, a solenoid for changing the light emission direction of the headlight, and the like) which are used in various control systems such as the aforementioned ARS and AFS. In some cases, from a safety standpoint, there are provided a light source (cornering lamp) for cornering which is used to improve visibility in turning by emitting light in the direction of inner wheels at the time of turning, a light source (daytime running lamp) for daytime lighting with which a vehicle makes its presence known to other vehicles even in the daytime to prevent an accident, and the like. Overall, the number of light sources provided in a vehicle is on the increase. Further, there have been an increasing number of cases where LEDs are used as light sources for headlights, taillights, and the like.
Operating electric power for each of loads such as described above is supplied from a vehicle-mounted battery. To supply power from the vehicle-mounted battery to a load, a fuse needs to be arranged in the power supply path therebetween for safety assurance. Accordingly, as the number of loads installed in a vehicle increases, the numbers of fuses and relays which must be provided in the relay/fuse box 200 also increases. As a result, there have arisen problems such as the increase in the size and cost of the relay/fuse box 200. In particular, in the case where the size of the relay/fuse box 200 increases, it becomes difficult to install the relay/fuse box 200 at the conventional installation position. This may cause various harmful effects such as a significant design change.
One conceivable approach for decreasing the size of the relay/fuse box 200 is, for example, to decrease the total number of fuses by using a single fuse for multiple loads for different uses. For example, it is conceivable that the light sources L2 to L4 are collectively connected to the fuse H2, unlike in FIG. 1 in which the fuses H2 to H4 are connected to the light sources L2 to L4, respectively. This makes it possible to omit the fuses H3 and H4.
However, when a short-circuit occurs in any one of the light sources L2 to L4, e.g., the light source L3, to cause a blowout of the fuse H2, the light sources L2 and L4 without abnormalities also become unusable. In other words, there arises the problem that multiple loads simultaneously become unusable when a fuse is blown. This becomes a big problem, particularly in the case where the multiple loads have different uses, respectively. In the aforementioned example, in the event of a short-circuit in the light source L3 for the width indicator, the light source L2 also becomes unusable which is the headlight more important than the width indicator. Accordingly, when consideration is given to safety, it is not favorable to collectively connect multiple loads (in particular, multiple loads for different uses) to a single fuse as described above.
The present invention has been made in view of the above-described points, and an object of the present invention is to provide a vehicle-mounted load controller, a vehicle-mounted headlight device, and a vehicle-mounted taillight device which enable the miniaturization of a relay/fuse box and which make it possible to prevent multiple loads from simultaneously becoming unusable.